Recently, demands for automation and higher performances of machine tools are increasing. In order to realize automation, automatic changer apparatuses are proposed such as an automatic tool changer (ATC) which automatically changes tools, and an automatic palette changer (APC) which automatically changes a palette on which a workpiece is mounted. In addition, peripheral apparatuses such as a workpiece supply apparatus such as a loader and a bar feeder are also widely known. In order to realize higher performance, in-machine measurement and intelligent system using sensors are also employed.
Further, in order to automate or improve performance of machine tools, in some cases, use of a robot is proposed. For example, JP 2010-36285 A discloses a technique in which a robot provided outside of the machine tool is used, to execute attachment and detachment of the workpiece to and from the machine tool. JP 2010-64158 A discloses a technique in which an articulated robot which travels on a gantry rail attached on an upper part of the machine tool is provided, and the transport of the workpiece or the like among a plurality of machine tools is executed by the articulated robot. JP H5-301141 A and JP H5-301142 A disclose a transporting tool of a workpiece which transports the workpiece by an open/close operation of a grip unit. The transporting tool has an arm shape, and is attached to a body function box. The body function box is also provided at a right side of a spindle head which supports a spindle. The transporting tool can pivot about an axis approximately orthogonal to a long axis of the spindle. The transporting tool can change, by the pivoting movement, between a state in which the arm is approximately horizontal and a state in which the arm is approximately vertical.
In the related art, however, no robot is described which can access the workpiece and tool with various positions and orientations. Specifically, normally, a body part of the machine tool is covered with a cover in view of safety and surrounding environment. Therefore, when it is desired to access an inside of a machining chamber using a robot provided at a location other than the body part of the machine tool as in JP 2010-36285 A and JP 2010-64158 A, a door of the machining chamber must be opened. Thus, with the robots of JP 2010-36285 A and JP 2010-64158 A, while it is possible to attach or detach the workpiece when the workpiece is not being machined, it is not possible for the robot to access the workpiece or the tool during the machining; that is, when the door of the machining chamber is closed. As a result, with the techniques of JP 2010-36285 A and JP 2010-64158 A, the usages of the robots are limited.
As described in JP H5-301141 A and JP H5-301142 A, there exist techniques in which a robot such as a transporting tool is fixed on a spindle head. According to such techniques, the robot can access the workpiece and the tool even in the state where the door of the machining chamber is closed. However, in this case, the position of the robot with respect to the spindle head is fixed, and thus, in order to allow access to the opposite side of the robot with the spindle head therebetween, the size of the robot must be increased. For example, when the robot is an articulated robot in which a plurality of arms are connected by joints, the lengths of the arms must be elongated. When any of the arms is elongated, however, interference with other members tends to occur more easily, and a torque necessary for moving the joints in also increased.
An advantage of the present disclosure lies in provision of a machine tool having a robot of a smaller size, which can access a workpiece and a tool in various positions and orientations.